1. Field of the Invention
The present invention relates to an oximeter system designed so that a correlation between body motion and occurrence of respiratory failure can be recognized accurately for a patient or a suspected patient having a respiratory disease such as chronic respiratory failure or quasi chronic respiratory failure.
2. Description of the Related Art
In diagnosing a patient having a respiratory disease, it is essential to accurately recognize a causal relation or a correlation between body motion and respiratory disease presentation of the patient to determine a suitable therapeutic measure such as selection of a therapeutic apparatus or prescription of an oxygen flow rate. Specifically, therapeutic measures are different among the patients depending on conditions as to whether a respiratory disease is presented at the time of an exercise while the patient is awake, the amount of exercise, i.e., the degree of exercise which may cause the respiratory disease, whether the respiratory disease is presented even while the patient is at rest, whether the respiratory disease is presented mainly while the patient is in sleep, or other condition. There is an approach of measuring a variation in oxygen saturation in an arterial blood (hereinafter, called as “blood oxygen saturation” or “SpO2”) of a subject including a patient, as an approach of recognizing a condition of the subject having a respiratory disease. This approach is proposed utilizing a phenomenon that a respiratory failure induces blockage of oxygen supply, which resultantly lowers the blood oxygen saturation.
Conventionally, as shown in FIG. 30, for instance, there has been an approach, in which the blood oxygen saturation of a subject is serially measured by attaching a pulse oximeter to the subject, and a daily behavior log of the subject which has been manually recorded by the subject or a nurse, and the time-based change of the blood oxygen saturation are cross-checked to recognize a correlation between body motion and presentation of a respiratory disease. FIG. 30 is a time chart, in which behavior events are logged on a measurement result of a continuous pulse oximetry. A judgment is made as to whether the blood oxygen saturation is lowered in association with the body motion of the subject based on the measurement data. If there is found a correlation between body motion and respiratory failure of the subject, use of home oxygen therapy (HOT) is considered, or an oxygen flow rate is prescribed. If there is not found a correlation between body motion and respiratory failure of the subject, use of nasal intermittent positive pressure ventilation (NIPPV) is considered.
There is known a system for concurrently measuring the blood oxygen saturation of a subject, and detecting a body motion of the subject. The system noninvasively confirms endothelial dysfunction, breathing disorder due to hypopnea during sleep, or upper airway resistance syndrome (UARS), as well as biophysical state of a subject regarding activity or reactivity of autonomic nervous system, or responsiveness to pharmacological agent. The system is provided with an actigraph for judging whether a subject is in sleep or awake, and a pulse oximeter for measuring a blood oxygen saturation of the subject to diagnose sleep apnea syndrome (SAS).
In diagnosing the disease based on the measurement data as shown in FIG. 30, a subject or a nurse is required to manually record a behavior log of the subject at the time when the blood oxygen saturation is measured by a pulse oximeter, which increases a labor involved in collecting the data. Also, it takes a certain time and labor in combining the measurement result by the pulse oximeter and the behavior log. Further, there is a case that it is difficult to judge whether lowering of the blood oxygen saturation is due to body motion because the recorded time of an event is uncertain, or an event has not been logged. The lowering degree of the blood oxygen saturation is normally varied due to a degree of body motion, an exercise time, or an exercise amount. Since the daily behavior is logged manually, it is difficult to objectively judge the exercise amount, which takes a time in prescribing an optimal oxygen flow rate.
The conventional arrangement discloses combination of an actigraph and a pulse oximeter as a sleep diagnostic system. However, the arrangement does recite or suggest application of the system to treating subjects of chronic respiratory failure or quasi chronic respiratory failure. This means that there has not been found a diagnostic approach regarding chronic respiratory failure and quasi chronic respiratory failure by correlating a measurement result of a pulse oximeter to a measurement result of an actigraph. In other words, there has not been found an approach of acquiring analysis data beneficial to a subject by linking a measurement result of an actigraph to a measurement result on blood oxygen saturation of a pulse oximeter.